Toy building block



FIG. 1 is a perspective view showing the front, right side and top of a toy building block showing my design;

FIG. 2 is a rear view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a top view thereof; and,

FIG. 5 is a bottom view thereof. 

The ornamental design for a toy building block, as shown. 